Sensor signal multiplexer and digitizer with analog notch filter and optimized sample frequency

ABSTRACT

The described technology is generally directed towards a sensor signal multiplexer and digitizer with analog notch filter and optimized sample frequency, and corresponding methods of use and manufacture. In some examples, the disclosed technologies can be used to reduce vibration sensitivity of an inertial measurement unit (IMU). The disclosed sensor signal multiplexer can sample sensor inputs on multiple input channels at a first, higher frequency, and integrate samples for each channel in order to generate lower frequency sensor outputs. The lower frequency sensor outputs can be converted to digital form.

CROSS REFERENCE TO RELATED APPLICATION

This is a nonprovisional claiming priority under 35 U.S.C. § 119 to U.S.Provisional Patent Application No. 63/228,206, filed on Aug. 2, 2021,entitled “Dual Integrator Round Robin.” The prior application isincorporated by reference in its entirety.

TECHNICAL FIELD

The subject disclosure generally relates to multi-channel sensors, moreparticularly, to electronics used to amplify and digitize outputs ofmulti-channel sensors.

BACKGROUND

Inertial measurement units (IMUs) that provide motion detection inelectronic devices such as mobile phones, virtual reality headsets, andother devices, may include multi- channel motion sensing technologies,wherein different channels are used to sense motion in differentdirections.

For example, some IMUs include micro electromechanical system (MEMS)sensors, which can detect motion along x, y, and z axes. An example MEMSsensor can include a suspended mass between pairs of capacitive plates.Each pair of capacitive plates is part of a respective sensing channelassociated with a respective axis. When tilt or acceleration is appliedto the MEMS sensor, movement of the suspended mass creates differencesin electric potential, which can be output via the different sensingchannels. The outputs of the different MEMS sensing channels can befurther processed by the IMU to produce digital outputs that indicatemotion.

Electronics for use by IMUs in processing outputs of multi-channelsensors, such as MEMS sensors, can be designed in several ways. In oneexample approach, dedicated hardware can be allocated to each sensingchannel. In another approach, time domain division can allow sharing ofhardware across the multiple sensing channels. While allocatingdedicated hardware to each sensing channel can lead to optimalperformance, sharing hardware across sensing channels can be more cost,power, and space efficient, and can also produce acceptable performance

Sharing hardware implies signal sampling, which can be done, forexample, in a “round robin” approach by sampling each channel insequence. One problem with the use of round robin sampling in IMUs isvibrational noise. For example, a device that is playing music, orotherwise in an environment with sound vibration, may experiencevibrational noise that affects motion detection by its IMU. Othersources of vibration such as vehicle engines, equipment operation, andthe like can also affect motion detection. In modern devices andsystems, IMUs are subject to many vibrational disturbances, due tocomponents such as speakers and choke inductances that generatesubstantial vibrations on device electronics.

Round robin architectures are sensitive to vibrational noiseinterference because of their intrinsic sampled transfer function, whichfolds the harmonics of the round robin frequency into the baseband. Theround robin frequency is commonly in the range of tens of kilohertz(kHz), which is in the same range as many vibrational disturbances. Forexample, many vibrational disturbances are in the 0-40 kHz range.

One solution to avoid the problem vibrational noise is to avoid the useof round robin architectures in IMUs. Another solution is to increasethe overall round robin frequency, including the analog to digitalconverter (ADC) sampling frequency. However, such solutions have thedrawbacks of increased power consumption and design complexity. There isa need for improved approaches to address the problems of vibrationalnoise in IMUs that use round-robin sampling.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting embodiments of the subject disclosure are described withreference to the following figures, wherein like reference numeralsrefer to like parts throughout the various views unless otherwisespecified:

FIG. 1 illustrates example higher frequency and lower frequency portionsof a sensor signal path, in accordance with various embodiments of thisdisclosure;

FIG. 2 illustrates an example inertial measurement unit (IMU) comprisinga sensor signal path in accordance with various embodiments of thisdisclosure;

FIG. 3 illustrates an example IMU equipped to use a frequency modulatedinput signal, in accordance with various embodiments of this disclosure;

FIG. 4 illustrates example timing of signal processing operations bycomponents of the IMU illustrated in FIG. 3 , in accordance with variousembodiments of this disclosure;

FIG. 5 illustrates an example MEMS transfer function with an additionalnotch added by a sensor signal path in accordance with variousembodiments of this disclosure; and

FIG. 6 illustrates an example method to process sensor signals, inaccordance with various embodiments of this disclosure.

DETAILED DESCRIPTION

Aspects of the subject disclosure will now be described more fullyhereinafter with reference to the accompanying drawings in which exampleembodiments are shown. In the following description, for purposes ofexplanation, numerous specific details are set forth in order to providea thorough understanding of the various embodiments. However, thesubject disclosure may be embodied in many different forms and shouldnot be construed as limited to the example embodiments set forth herein.

One or more aspects of the technology described herein are generallydirected towards a sensor signal multiplexer and digitizer with analognotch filter and optimized sample frequency, and corresponding methodsof use and manufacture. In some examples, the disclosed technologies canbe used to reduce vibration sensitivity of an inertial measurement unit(IMU). The disclosed sensor signal multiplexer can sample sensor inputson multiple input channels at a first, higher frequency, and integratesamples for each channel in order to generate lower frequency sensoroutputs. The lower frequency sensor outputs can be converted to digitalform. Further aspects and embodiments are described in detail below.

FIG. 1 illustrates an example sensor signal path comprising higherfrequency and lower frequency portions thereof, in accordance withvarious embodiments of this disclosure. The example sensor signal path100 comprises a multiplexer 111, an amplifier 112, a filter 120, ananalog to digital converter (ADC) 131, and a digital demultiplexer 132.The multiplexer 111 and the amplifier 112 are indicated as operating ata higher frequency 110, while the ADC 131 is indicated as operating at alower frequency 130. The filter 120 enables the transition from thehigher frequency 110 to the lower frequency 130.

The sensor signal path 100 can receive sensor inputs, e.g., sensorinputs from multiple different MEMS channels, which are illustrated asMEMS X 101, MEMS Y 102, and MEMS Z 103. The sensor signal path 100 canoutput digital sensor outputs such as OUT X 141, OUT Y 142, and OUT Z143. The output OUT X 141 can comprise a digital version of the inputMEMS X 101, and likewise, the output OUT Y 142 can comprise a digitalversion of the input MEMS Y 102, and the output OUT Z 143 can comprise adigital version of the input MEMS Z 103.

In example operations according to FIG. 1 , the multiplexer 111 canreceive multiple sensor inputs MEMS X 101, MEMS Y 102, and MEMS Z 103.The multiplexer 111 can sample the multiple sensor inputs MEMS X 101,MEMS Y 102, and MEMS Z 103, e.g., using round-robin sampling, and themultiplexer 111 can produce a multiplexed output comprising a stream ofsamples from the multiple sensor inputs MEMS X 101, MEMS Y 102, and MEMSZ 103. The multiplexer 111 can perform sampling at the higher frequency110, and so its output stream of samples can likewise be at the higherfrequency 110. The amplifier 112 can amplify the stream of samplesproduced by the multiplexer 111, thereby producing an amplified streamof samples from the multiple sensor inputs MEMS X 101, MEMS Y 102, andMEMS Z 103. The amplified stream of samples can likewise be at thehigher frequency 110.

The filter 120 can be implemented as illustrated in FIG. 2 and FIG. 3 .In general, the filter 120 can use integrators to combine samplesassociated with each of the respective sensor inputs MEMS X 101, MEMS Y102, and MEMS Z 103. For example, samples associated with MEMS X 101 canbe combined, samples associated with MEMS Y 102 can be combined, andsamples associated with MEMS Z 102 can be combined, in a manner thatreduces the higher frequency 110 to the lower frequency 130.

The ADC 131 can convert the lower frequency 130 signals enabled byfilter 120 to digital form. The demultiplexer 132 can separate thedigital output from the ADC 131 into different outputs OUT X 141, OUT Y142, and OUT Z 143, which correspond to the different inputs MEMS X 101,MEMS Y 102, and MEMS Z 103, as noted above. The different outputs OUT X141, OUT Y 142, and OUT Z 143 can be used for example by a device thatincorporates the illustrated sensor signal path 100, in order todetermine motion of the device.

In an aspect, the disclosed solution comprises an analog chain whichallows the use of two different frequencies, a higher frequency 110 forthe input channel MUX 111, and a lower frequency 130 for the ADC 131,without incurring folding issues that can occur in the ADC 131. Usingthe disclosed sensor signal path 100, it is possible to take advantageof a low-speed ADC 131 which can have lower power consumption and easierdesign flow than a high-speed ADC. Furthermore, the disclosed sensorsignal path 100 can avoid problems of vibrational noise, because thehigher frequency 110 can comprise a frequency that is above the typicalenvironmental noise experienced by devices in the field. The disclosedsensor signal path 100 therefore enables the use of a round-robinarchitecture which can perform as well as three-channel solutions whichuse dedicated hardware for each of the inputs MEMS X 101, MEMS Y 102,and MEMS Z 103 rather than round-robin sampling, as employed by thesensor signal path 100.

FIG. 2 illustrates an example inertial measurement unit (IMU) comprisinga sensor signal path in accordance with various embodiments of thisdisclosure. The example IMU 200 includes sensor(s) 210 and a sensorsignal path 220. The sensor(s) 210 can output multiple sensor outputs,which are received at sensor signal path 220 as inputs 211, 212 . . . m.The sensor signal path 220 comprises a multiplexer 221, an amplifier222, a demultiplexer 223, integrators 224, 225 . . . k, a multiplexer227, an ADC 228, and a digital processor/demultiplexer 229. The sensorsignal path 220 can output digital outputs 231, 232 . . . m, whichcorrespond to the inputs 211, 212 . . . m.

Embodiments according to FIG. 2 can generally operate as described abovein connection with FIG. 1 . FIG. 2 illustrates an example structure ofthe filter 120 introduced in FIG. 1 . The filter 120 can be implementedfor example via demultiplexer 223, integrators 224, 225 . . . k, andmultiplexer 227. Furthermore, FIG. 2 illustrates a more genericembodiment in which the sensor(s) 210 need not necessarily beimplemented as MEMS sensors, and the number of input channels is notconstrained. In general, any number (m) of input channels can beprocessed by the sensor signal path 220, using a number of integrators(k) which can be fewer than the number (m) of input channels. The number(m) of output channels can be the same as the number (m) of inputchannels.

Operations according to FIG. 2 can comprise, e.g., in addition to theoperations described above with reference to FIG. 1 , demultiplexing, bythe demultiplexer 223, the amplified input stream which is output fromthe amplifier 222. The demultiplexer 223 can provide demultiplexedoutputs to each of the integrators 224, 225 . . . k. Each of theintegrators 224, 225 . . . k can be configured to combine demultiplexedoutputs received from the demultiplexer 223, to output the resultingcombinations to the multiplexer 227, and to then reset, in order tobegin a new combination of demultiplexed outputs received from thedemultiplexer 223. The timing of the integrators 224, 225 . . . k can beimplemented such that samples associated with each respective input 211,212 . . . m are combined by an integrator 224, 225 . . . k prior toreset of the integrator.

In an example embodiment according to FIG. 2 , a sensor signal path 220can comprise a multiplexer 221 configured to receive a plurality ofsensor signals, e.g., inputs 211, 212 . . . m, at a first samplefrequency (the higher frequency 110), wherein the multiplexer 221generates a multiplexed output. The plurality of sensor signals 211, 212. . . m can be generated by a plurality of sensors 210, and theplurality of sensors 210 can comprise a number of sensors that is morethan the total number k of integrators 224, 225 . . . k.

An amplifier 222 can be coupled between the multiplexer 221 and thedemultiplexer 223, wherein the amplifier 222 is configured to amplifythe multiplexed output from the multiplexer 221. The demultiplexer 223can be configured to demultiplex the multiplexed output from themultiplexer 221 and amplifier 222, resulting in a plurality ofdemultiplexed sensor signals. The multiplexer 221, amplifier 222, anddemultiplexer 223 can be configured to operate at the first samplefrequency (the higher frequency 110).

The plurality of integrators 224, 225 . . . k can comprise a totalnumber k of integrators that is less than or equal to the total number mof sensor signals of the plurality of sensor signals 211, 212 . . . m.The plurality of integrators 224, 225 . . . k can be configured toaccumulate samples of the plurality of demultiplexed sensor signals(output from demultiplexer 223), and to generate integrated outputs.Each respective integrator of the plurality of integrators 224, 225 . .. k can be configured to reset after accumulating a number of thesamples, as described in connection with FIG. 4 .

A second multiplexer 227 can be coupled between the plurality ofintegrators 224, 225 . . . k and the ADC 228, wherein the secondmultiplexer 227 can be configured to multiplex the integrated outputs ofthe plurality of integrators 224, 225 . . . k. The ADC 228 can beconfigured to generate a digital signal based on samples of theintegrated outputs of the plurality of integrators 224, 225 . . . k,wherein the digital signal comprises a second sample frequency (thelower frequency 130) that is lower than the first sample frequency 110,and wherein the second sample frequency 130 can for example be equal tothe first sample frequency 110 divided by a number of samplesaccumulated by an integrator of the plurality of integrators 224, 225 .. . k prior to resetting the integrator. The plurality of integrators224, 225 . . . k and the ADC 228 can be configured to operate at thesecond frequency 130. A demultiplexer 229 can be configured to samplethe digital signal output from ADC 228 and output the digital signal viaseparate channels, e.g., outputs 231, 232 . . . m, wherein each of theseparate channels 231, 232 . . . m corresponds to a sensor signal of theplurality of sensor signals 211, 212 . . . m.

In another embodiment which can be understood by reference to FIG. 2 ,the sensor signal path 220 can comprise a sensor signal multiplexer anddigitizer, which can be included, e.g., within an IMU 200. The IMU 200can further comprise multiple MEMS sensors, e.g., sensors 210, each MEMSsensor comprising a respective sensor output connection to producesensor outputs (received as inputs 211, 212 . . . m). The IMU 200 can beadapted for deployment in a mobile device, an augmented reality orvirtual reality headset, a vehicle, or other equipment.

The sensor signal path 220 comprises a sensor signal multiplexer 221comprising multiple sensor signal multiplexer 221 input connections anda sensor signal multiplexer 221 output connection, wherein the multiplesensor signal multiplexer 221 input connections are couplable withmultiple sensor 210 output connections in order to receive multiplesensor outputs 211, 212 . . . m. The sensor signal multiplexer 2221 canbe configured to sample the multiple sensor outputs 211, 212 . . . m andto output resulting samples via the sensor signal multiplexer 221 outputconnection. The sensor signal multiplexer 221 can be configured to useround-robin sampling to sample the multiple sensor outputs 211, 212 . .. m. The sensor signal multiplexer 221 can be configured to sample themultiple sensor outputs 211, 212 . . . mat a first frequency 110. Themultiple sensor outputs 211, 212 . . . m can comprise frequencymodulated signals as shown in FIG. 3 .

A signal amplifier 222 can comprise a signal amplifier 222 inputconnection and a signal amplifier 222 output connection, wherein thesignal amplifier 222 input connection is coupled with the inputmultiplexer 221 output connection. A demultiplexer 223 can comprise ademultiplexer 223 input connection and multiple demultiplexer 223 outputconnections, wherein the demultiplexer 223 input connection is coupledwith the signal amplifier 222 output connection.

Multiple integrators 224, 225 . . . k can be included, each integratorcomprising a respective integrator input connection, e.g., respectiveintegrator 224 input connection, and a respective integrator outputconnection, e.g., respective integrator 224 output connection, whereineach respective integrator input connection is coupled with a respectivedemultiplexer 223 output connection of the multiple demultiplexer 223output connections.

An integrator multiplexer 227 can comprise multiple integratormultiplexer 227 input connections and an integrator multiplexer 227output connection, wherein each respective integrator multiplexer 227input connection is coupled with a respective integrator outputconnection, e.g., respective integrator 224 output connection. Theintegrator multiplexer 227 can be configured to output, via theintegrator multiplexer 227 output connection, an integrator multiplexer227 output having a second frequency, wherein the first frequency 110 ishigher than the second frequency 130.

An ADC 228 can comprise an ADC 228 input connection and an ADC 228output connection, wherein the ADC 228 input connection is coupled withthe integrator multiplexer 227 output connection, and wherein the ADC228 is configured to produce a digital output comprising a digitizedversion of the multiple sensor outputs 211, 212 . . . m. In someembodiments, either the sensor signal path 220 or the IMU 200 canfurther comprise a digital demultiplexer 229 comprising a digitaldemultiplexer 229 input connection and multiple digital demultiplexer229 output connections for outputs 231, 232 . . . m, wherein the digitaldemultiplexer 229 input connection is coupled with the ADC 228 outputconnection.

FIG. 3 illustrates an example IMU equipped to use a frequency modulatedinput signal, in accordance with various embodiments of this disclosure.FIG. 3 comprises sensors X MEMS 301, Y MEMS 302, and Z MEMS 303. A drive320 provides a frequency modulated input signal. The sensors 301, 302,and 303 are coupled with a multiplexer 304, which is coupled with anamplifier (C2V) 305. The amplifier 305 is coupled with a demultiplexer306, which is coupled with integrators 307, 308. The integrators 307,308 are coupled with a multiplexer 309, which is in turn coupled with asuccessive approximation register analog to digital converter (SAR ADC)310. A drive 320 provides a modulated input signal which drives thesensors X MEMS 301, Y MEMS 302, and Z MEMS 303.

In FIG. 3 , the example frequency modulated input signal is at 153.6kHz. The sensors 301, 302, and 303, the multiplexer 304, the amplifier305, and the demultiplexer 306 can operate at the frequency of thefrequency modulated input signal. The integrators 307, 308, themultiplexer 309, and the SAR ADC 310 can operate at the lower frequency,as shown. The integrators 307, 308 can reset according to reset signals,received as rst1 and rst2.

In general, operations according to FIG. 3 can comprise sampling, by theinput multiplexer 304, a number “m” of multiple inputs (where m=3 inFIG. 3 ) at a sampling frequency F_(s). The signal amplifier 305 canreceive the multiplexed output of the input multiplexer 304 and amplifyit. The demultiplexer 306 can receive the amplified signal from theamplifier 305 and can alternatingly route the amplified signal tointegrators of the set of integrators 307, 308.

The set of integrators 307, 308 can comprise a number “k” ofintegrators, with k≤m (where k=2 in FIG. 3 ). In other words, the numberk of integrators can be equal to or less than the number m of inputs.Each integrator 307, 308 can accumulate a finite number “n” of samplesbefore being reset, where n>1. The accumulation of the finite number “n”of samples effects a notch filter whose notch frequency is set toF_(s)/(n*m), as further illustrated in FIG. 5 .

The multiplexer 309 can optionally be implemented by an ADC in someembodiments. The multiplexer 309 can sample the “k” integrator outputsat a sampling frequency of F_(s)/n, with a sequence such as illustratedin FIG. 4 . The SAR ADC 310 can comprise a digital demultiplexerconfigured to split the stream output of the multiplexer 309 into “m”separated channels, wherein each of the output channels corresponds toan input of the “m” inputs.

The embodiment illustrated in FIG. 3 can implement an analog signal pathof a high-performance accelerometer. FIG. 3 uses m=3 channels,corresponding to X, Y and Z acceleration axes, which are sampled throughan input multiplexer 304 at F_(s)=153.6 kHz (51.2 kHz per axis), andthen amplified with a charge amplifier (C2V) 305. The input signal ismodulated at 153.6 kHz, thus after C2V 305, a mixer 305A can be used todemodulate the signal in baseband. In FIG. 3 , k=2 integrators are used,and each of them sums n=samples of each channel before being reset.

Due to the accumulation process, the integrators introduce a notch atF_(s)/(m*n)=153.6 kHz/(2*3)=25.6 kHz in each channel's transferfunction, as illustrated in FIG. 5 . The SAR ADC 310 samples the signalscoming from the two integrators at 76.8 kHz, corresponding to 25.6 kHzper channel. A digital demultiplexer can split the ADC stream at 76.8kHz in three different streams at 25.6 kHz, corresponding to X, Y and Zaxes.

FIG. 4 illustrates example timing of signal processing operations bycomponents of the IMU illustrated in FIG. 3 , in accordance with variousembodiments of this disclosure. FIG. 4 includes rows and columns. Thecolumns are arranged in a time sequence according to timing of inputsamples, wherein an example time unit is illustrated in the bottom row.The rows show operations of various different components, including theC2V 305, the demultiplexer 306, the integrator “1” (i.e., the integrator307), the integrator “2” (i.e. the integrator 308), an ADC sample andhold component that can implement the multiplexer 309, and the ADC 310.

FIG. 4 illustrates output of the C2V 305 as a stream of amplifiedsamples comprising, from right to left, a sample from input x (X MEMS301), followed by a sample from input z (Z MEMS 303), followed by asample from input y (Y MEMS 302), and further repetitions of the x, z, ysample sequence. The demultiplexer 306 sends two of the samples from theC2V 305 to integrator 2 308, followed by sending two samples to theintegrator 1 307, and further repetitions of the alternation betweenintegrator 2 308 and integrator 1 307.

Each of the integrators 308 and 307 is illustrated as alternatinglyreceiving samples from the demultiplexer 306, followed by being on“hold” while the other integrator receives its samples from thedemultiplexer 306. Thus, for example, the integrator 1 307 is on holdwhile integrator 2 308 receives a sample x, followed by a sample z. Theintegrator 1 307 then receives a sample y followed by a sample x. Theintegrator 1 307 then goes on hold while integrator 2 308 receives asample z, followed by a sample y, and so on as illustrated.

Integrator resets are illustrated in the ADC S&H row. The ADC S&H rowillustrates an initial reset of integrator 2 308. The integrator 2 308can output its accumulated x samples to the ADC 310, and reset.Following the reset of integrator 2 308, the integrator 2 308 beginsaccumulating z samples, as illustrated in the integrator 2 308 row. TheADC S&H row illustrates a next reset of integrator 1 307. The integrator1 307 can output its accumulated y samples to the ADC 310, and reset.Following the reset of integrator 1 307, the integrator 1 307 beginsaccumulating x samples, as illustrated in the integrator 1 307 row. TheADC S&H row illustrates a next reset of integrator 2 308. The integrator2 308 can output its accumulated z samples to the ADC 310, and reset.Following the reset of integrator 2 308, the integrator 2 308 beginsaccumulating y samples, as illustrated in the integrator 2 308 row.Thus, each of the integrators accumulates samples from a given sensorinput, then outputs those samples, and resets. FIG. 4 illustrates anembodiment comprising two integrators; however the example can beextended to the use of additional integrators if desired.

FIG. 5 illustrates an example MEMS transfer function with an additionalnotch added by a sensor signal path in accordance with variousembodiments of this disclosure. FIG. 5 is a graph showing amplitude, indecibels (dB) on the vertical axis and input frequency, in kHz, on thehorizontal axis. Dashed vertical lines illustrate intervals of 25.6 kHz.The MEMS transfer function is the smooth upper line plotted on thegraph. MEMS plus signal path shows the effect of using a signal pathsuch as illustrated in FIG. 3 , with three inputs (m=3), two integrators(k=2), and a sampling frequency F_(s) of 153.6 kHz.

FIG. 6 illustrates an example method to process sensor signals, inaccordance with various embodiments of this disclosure. For simplicityof explanation, the illustrated method is depicted and described as aseries of acts. It is to be understood and appreciated that variousembodiments disclosed herein need not be limited by the acts illustratedand/or by the order of acts. For example, acts can occur in variousorders and/or concurrently, and with other acts not presented ordescribed herein. Furthermore, not all illustrated acts may be requiredto implement methodologies in accordance with the disclosed subjectmatter. In addition, those skilled in the art will understand andappreciate that the methods illustrated herein could alternatively berepresented as a series of interrelated states via a state diagram orevents.

The operations illustrated in FIG. 6 can be performed, e.g., by a signalpath 220 such as illustrated in FIG. 2 . At 602, the multiplexer 221 canreceive a plurality of sensor signals, e.g., inputs 211, 212 . . . mwherein each sensor signal of the plurality of sensor signals 211,212... m comprises a first sampling frequency, such as the frequencyillustrated in FIG. 3 . The plurality of sensor signals 211, 212 . . . mcan be received from sensors 210, e.g., microelectromechanical system(MEMS) sensors as illustrated in FIG. 3 .

At 604, the multiplexer 221 can sample the plurality of sensor signals211, 212 . . . m at the first sampling frequency, resulting in sensoroutput samples. Sampling the plurality of sensor signals 211, 212 . . .m can comprise round-robin sampling. At 606, the multiplexer 221 canmultiplex the plurality of sensor signals 211, 212 . . . m, resulting ina multiplexed sensor output. At 608, the amplifier 222 can amplify themultiplexed sensor output, resulting in an amplified multiplexed sensoroutput.

At 610, the demultiplexer 223 can demultiplex the amplified multiplexedsensor output (from amplifier 222), resulting in multiple componentamplified sensor outputs.

The demultiplexer 223 can alternatingly send component amplified sensoroutputs to integrators 224, 225 . . . k, as illustrated in FIG. 4 .

At 612, the integrators 224, 225 . . . k can accumulate respectivesamples from each respective sensor signal of the plurality of sensorsignals 211, 212 . . . m. Accumulating respective samples from eachrespective sensor signal of the plurality of sensor signals 211, 212 . .. m can comprise accumulating respective samples from the multiplecomponent amplified sensor outputs, i.e., the outputs of thedemultiplexer 223.

At 614, the integrators 224, 225 . . . k can integrate accumulatedrespective samples of each respective sensor signal 211, 212 . . . m,resulting in respective integrated outputs, wherein the respectiveintegrated outputs comprise a second sampling frequency that is lowerthan the first sampling frequency, e.g., as can be understood byreference to FIG. 4 .

At 616, the multiplexer 227 can multiplex the respective integratedoutputs, resulting in a multiplexed integrated sensor output. At 618,the ADC 228 can convert the respective integrated outputs to a digitalformat. Converting the respective integrated outputs to the digitalformat can comprise converting the multiplexed integrated sensor output,from multiplexer 227, to the digital format. At 620, the demultiplexer229 can demultiplex the multiplexed integrated sensor output afterconverting (by the ADC 228) the multiplexed integrated sensor output tothe digital format, resulting in multiple component digital integratedsensor outputs 231, 232 . . . m.

Another example method, which can also be understood by reference toFIG. 2 , can comprise a sensor signal multiplexer and digitizer method,such as may be performed by an IMU. The IMU can be adapted fordeployment, e.g., in a mobile device, an augmented reality or virtualreality headset, or a vehicle. The example method can comprise sampling,by the multiplexer 221, outputs of multiple sensors 210, resulting insensor output samples. The multiple sensors 210 can comprise, e.g., MEMSsensors. The outputs of the multiple sensors 210 can comprise frequencymodulated signals. Sampling the outputs of the multiple sensors 210 cancomprise round-robin sampling. Furthermore, sampling the outputs of themultiple sensors 210 can be performed at a first frequency, e.g., thehigher frequency 110 illustrated in FIG. 1 .

The example method can comprise multiplexing, by the multiplexer 221,the sensor output samples, resulting in a multiplexed sensor output fromthe multiplexer 221. The example method can furthermore compriseamplifying, by the amplifier 222, the multiplexed sensor output from themultiplexer 221, resulting in an amplified multiplexed sensor output.

The example method can furthermore comprise demultiplexing, by thedemultiplexer 223, the amplified multiplexed sensor output from theamplifier 222, resulting in multiple component amplified sensor outputsfrom the demultiplexer 223. The example method can furthermore compriseintegrating, by the integrators 224, 225 . . . k, each of the multiplecomponent amplified sensor outputs from the demultiplexer 223, resultingin multiple component integrated sensor outputs from the integrators224, 225 . . . k. Integrating each of the multiple component amplifiedsensor outputs from the integrators 224, 225 . . . k can compriseresetting an integrator, accumulating, by the integrator, multiplesamples included within a component amplified sensor output, resultingin accumulated samples, and outputting, by the integrator, theaccumulated samples.

The example method can furthermore comprise multiplexing, by themultiplexer 227, the multiple component integrated sensor outputs fromthe integrators 224, 225 . . . k, resulting in a multiplexed integratedsensor output from the multiplexer 227. The multiplexed integratedsensor output can have a second frequency, e.g., the higher frequency130 illustrated in FIG. 1 , wherein the first frequency 110 is higherthan the second frequency 130.

The example method can furthermore comprise performing. By ADC 228, ananalog to digital conversion of the multiplexed integrated sensor outputfrom the multiplexer 227, resulting in a digital integrated sensoroutput from the ADC 228. The digital integrated sensor output from theADC 228 can comprise a digital multiplexed integrated sensor output. Theexample method can furthermore comprise demultiplexing, by thedemultiplexer 229, the digital multiplexed integrated sensor output fromthe ADC 228, resulting in multiple component digital integrated sensoroutputs 231, 232 . . . m.

As employed in the subject specification, the term “component” refers tosubstantially any analog and/or digital based device(s), circuit(s),etc. comprising, e.g., a resistor, a capacitor, a transistor, a diode,an inductor, a memory, a programmable device, e.g., fuse, fieldprogrammable gate array (FPGA), complex programmable logic device(CPLD), etc. relevant to performing operations and/or functions ofcircuit(s), device(s), system(s), etc. disclosed herein. Further, theterms “processing component”, “control unit component”, “control unit”,and “arithmetic logic unit (ALU)” can refer to substantially anycomputing processing unit or device (e.g., MAC, etc.), comprising, butnot limited to comprising, single-core processors; single-processorswith software multithread execution capability; multi-core processors;multi-core processors with software multithread execution capability;multi-core processors with hardware multithread technology; parallelplatforms; and parallel platforms with distributed shared memory.Additionally, a processor can refer to an integrated circuit, an ASIC, adigital signal processor (DSP), an FPGA, a programmable logic controller(PLC), a CPLD, a discrete gate or transistor logic, discrete hardwarecomponents, an analog circuit, or any combination thereof designed toperform the functions and/or processes described herein. Further, aprocessor can exploit nano-scale architectures such as, but not limitedto, molecular and quantum-dot based transistors, switches and gates,e.g., in order to optimize space usage or enhance performance of mobiledevices. A processor can also be implemented as a combination ofcomputing processing units, devices, etc.

In the subject specification, the term “memory”, “memory component”,“lookup table (LUT)” and substantially any other information storagecomponent relevant to operation and functionality of devices disclosedherein refer to “memory components,” or entities embodied in a “memory,”or components comprising the memory. It will be appreciated that thememory can include volatile memory and/or nonvolatile memory. By way ofillustration, and not limitation, volatile memory, can include randomaccess memory (RAM), which can act as external cache memory. By way ofillustration and not limitation, RAM can include synchronous RAM (SRAM),dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM(DDR SDRAM), enhanced SDRAM (ESDRAM), Synchlink DRAM (SLDRAM), Rambusdirect RAM (RDRAM), direct Rambus dynamic RAM (DRDRAM), and/or Rambusdynamic RAM (RDRAM). In other embodiment(s) nonvolatile memory caninclude read only memory (ROM), programmable ROM (PROM), electricallyprogrammable ROM (EPROM), electrically erasable ROM (EEPROM), or flashmemory. Additionally, the components and/or devices disclosed herein cancomprise, without being limited to comprising, these and any othersuitable types of memory.

Reference throughout this specification to “one embodiment,” or “anembodiment,” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment. Thus, the appearances of the phrase “in oneembodiment,” or “in an embodiment,” in various places throughout thisspecification are not necessarily all referring to the same embodiment.Furthermore, the particular features, structures, or characteristics maybe combined in any suitable manner in one or more embodiments.

Furthermore, to the extent that the terms “includes,” “has,” “contains,”and other similar words are used in either the detailed description orthe appended claims, such terms are intended to be inclusive—in a mannersimilar to the term “comprising” as an open transition word—withoutprecluding any additional or other elements. Moreover, the term “or” isintended to mean an inclusive “or” rather than an exclusive “or”. Thatis, unless specified otherwise, or clear from context, “X employs A orB” is intended to mean any of the natural inclusive permutations. Thatis, if X employs A; X employs B; or X employs both A and B, then “Xemploys A or B” is satisfied under any of the foregoing instances. Inaddition, the articles “a” and “an” as used in this application and theappended claims should generally be construed to mean “one or more”unless specified otherwise or clear from context to be directed to asingular form.

Aspects of systems, apparatus, devices, processes, and process blocksexplained herein can be embodied within hardware, such as an ASIC or thelike. Moreover, the order in which some or all of the process blocksappear in each process should not be deemed limiting. Rather, it shouldbe understood by a person of ordinary skill in the art having thebenefit of the instant disclosure that some of the process blocks can beexecuted in a variety of orders not illustrated.

Furthermore, the word “exemplary” and/or “demonstrative” is used hereinto mean serving as an example, instance, or illustration. For theavoidance of doubt, the subject matter disclosed herein is not limitedby such examples. In addition, any aspect or design described herein as“exemplary” and/or “demonstrative” is not necessarily to be construed aspreferred or advantageous over other aspects or designs, nor is it meantto preclude equivalent exemplary structures and techniques known tothose of ordinary skill in the art having the benefit of the instantdisclosure.

The above description of illustrated embodiments of the subjectdisclosure is not intended to be exhaustive or to limit the disclosedembodiments to the precise forms disclosed. While specific embodimentsand examples are described herein for illustrative purposes, variousmodifications are possible that are considered within the scope of suchembodiments and examples, as those skilled in the relevant art canrecognize.

In this regard, while the disclosed subject matter has been described inconnection with various embodiments and corresponding Figures, whereapplicable, it is to be understood that other similar embodiments can beused or modifications and additions can be made to the describedembodiments for performing the same, similar, alternative, or substitutefunction of the disclosed subject matter without deviating therefrom.Therefore, the disclosed subject matter should not be limited to anysingle embodiment described herein, but rather should be construed inbreadth and scope in accordance with the appended claims below.

What is claimed is:
 1. A sensor signal path, comprising: a multiplexerconfigured to receive a plurality of sensor signals at a first samplefrequency, wherein the multiplexer generates a multiplexed output; ademultiplexer configured to demultiplex the multiplexed output,resulting in a plurality of demultiplexed sensor signals; a plurality ofintegrators comprising a total number of integrators that is less thanor equal to a total number of sensor signals of the plurality of sensorsignals, wherein the plurality of integrators is configured toaccumulate samples of the plurality of demultiplexed sensor signals, andto generate integrated outputs; and an analog to digital convertorconfigured to generate a digital signal based on samples of theintegrated outputs of the plurality of integrators, wherein the digitalsignal comprises a second sample frequency that is lower than the firstsample frequency, and wherein the second sample frequency is equal tothe first sample frequency divided by a number of samples accumulated byan integrator of the plurality of integrators prior to resetting theintegrator.
 2. The sensor signal path of claim 1, further comprising asecond demultiplexer configured to sample the digital signal and outputthe digital signal via separate channels, wherein each of the separatechannels corresponds to a sensor signal of the plurality of sensorsignals.
 3. The sensor signal path of claim 1, further comprising anamplifier coupled between the multiplexer and the demultiplexer, whereinthe amplifier is configured to amplify the multiplexed output.
 4. Thesensor signal path of claim 1, further comprising a second multiplexercoupled between the plurality of integrators and the analog to digitalconverter, wherein the second multiplexer is configured to multiplex theintegrated outputs of the plurality of integrators.
 5. The sensor signalpath of claim 1, wherein the multiplexer and the demultiplexer areconfigured to operate at the first sample frequency.
 6. The sensorsignal path of claim 1, wherein the plurality of integrators and theanalog to digital convertor are configured to operate at the secondfrequency.
 7. The sensor signal path of claim 1, wherein each respectiveintegrator of the plurality of integrators is configured to reset afteraccumulating a number of the samples.
 8. The sensor signal path of claim1, wherein plurality of sensor signals are generated by a plurality ofsensors, and wherein the plurality of sensors comprises a number ofsensors that is more the total number of integrators.
 9. A method toprocess sensor signals, comprising: receiving a plurality of sensorsignals, wherein each sensor signal of the plurality of sensor signalscomprises a first sampling frequency; accumulating respective samplesfrom each respective sensor signal of the plurality of sensor signals;integrating accumulated respective samples of each respective sensorsignal, resulting in respective integrated outputs, wherein therespective integrated outputs comprise a second sampling frequency thatis lower than the first sampling frequency; and converting therespective integrated outputs to a digital format.
 10. The method toprocess sensor signals of claim 9, further comprising sampling theplurality of sensor signals at the first sampling frequency, resultingin sensor output samples.
 11. The method to process sensor signals ofclaim 10, wherein sampling the plurality of sensor signals comprisesround-robin sampling.
 12. The method to process sensor signals of claim10, further comprising multiplexing the plurality of sensor signals,resulting in a multiplexed sensor output.
 13. The method to processsensor signals of claim 12, further comprising amplifying themultiplexed sensor output, resulting in an amplified multiplexed sensoroutput.
 14. The method to process sensor signals of claim 13, furthercomprising demultiplexing the amplified multiplexed sensor output,resulting in multiple component amplified sensor outputs, and whereinaccumulating respective samples from each respective sensor signal ofthe plurality of sensor signals comprises accumulating respectivesamples from the multiple component amplified sensor outputs.
 15. Themethod to process sensor signals of claim 9, further comprisingmultiplexing the respective integrated outputs, resulting in amultiplexed integrated sensor output, and wherein converting therespective integrated outputs to the digital format comprises convertingthe multiplexed integrated sensor output to the digital format.
 16. Themethod to process sensor signals of claim 15, further comprisingdemultiplexing the multiplexed integrated sensor output after convertingthe multiplexed integrated sensor output to the digital format,resulting in multiple component digital integrated sensor outputs. 17.The method to process sensor signals of claim 9, wherein the pluralityof sensor signals are received from microelectromechanical system (MEMS)sensors.